1. Field of the Invention
The present invention relates to device operably connecting a precolumn with an analytical column in a chromatography system, and, more especially in a liquid chromatography system, together with the use of such device in an automatic industrial or laboratory chromatograph.
2. Description of the Prior Art
In chromatography, and in particular in liquid phase chromatography, the analysis of samples containing heavy compounds which are undesirable for the purpose of the analysis, or which must be identified separately, or the analysis of samples that are suspensions or analysis of samples containing highly dilute compounds, require the combination of a precolumn with the analytical column. The precolumn is to effect a preliminary treatment upon the sample prior to its injection in the separation column.
Depending upon the analytical problem in question, the precolumn and the column may be traversed by a fluid, in series or separately from each other.
The precolumn and the column may be flushed in series, for example, to effect the filtration of a sample in the form of a suspension or to retain heavy compounds. The columns may be flushed separately; for example, in a first phase, the precolumn may alone be flushed, with or without recycling, by the sample containing dilute compounds, in order to retain same, the column being traversed by the vector or carrier fluid, and, in a second phase, the precolumn and the column are traversed in series in order to elute the compounds retained in the precolumn and to inject them into the separation column. The precolumn and the column may also be flushed separately when it is desired to eliminate or elute from the precolumn the products retained therein, such as, for example, heavy compounds, or products in suspension in the samples having been filtered; the precolumn is then flushed from bottom to top, the separation column being flushed by the flow of the vector liquid.
Thus, so that the precolumn and the column may be traversed in series or separately and that there will be no false or incorrect moves during the establishment of the different connections, the precolumn and the column are connected with each other and with the different fluid conduits by means of any suitable valves and capillary tubes.
The immediately aforesaid means to establish the different connections has the disadvantages of being complicated (valves, joints, etc.) and of introducing appreciable loss of precolumn efficiency due to the inevitable dead spaces in the connections between the outlet of the precolumn and the inlet of the separation column.
Generally compare U.S. Pat. No. 3,592,046, Cantwell, Analytical Chemistry, 48, No. 13, pp. 1854-1859 (Nov. 1976), French Pat. No. 1,269,160, and German Auslegeschrift No. 26 55 387.